I did a ps pump on my yukon xl last summer. The directions included in the box from AC delco stated that after install I should fill the reservoir, jack up the front end so both wheels were off the ground and turn the wheel from lock to lock 30 times BEFORE starting the truck. I thought it was odd, but I did what it said. I had no foaming at all when I started the truck and the system was basically bled at that point. This was a new method to me. But, it worked great. When I worked in the garage we had a problem bleeding a pump on a vehicle. We used the old cap and drilled a hole in it. Then we inserted a pipe nipple and connected it to a hand held vacuum pump. We started the vehicle and pumped the vacuum pump to create a vacuum in the system. Let it idle for 15 minutes with 20 lbs of vacuum and the system was bled.

Well, it seems as being on an incline is the way to go (Haynes does not state this).

It does say that when turning the wheels from side to side, to NOT go far enough to hit the bump stops....I am assuming that the LOCK position would be before this?

Also...Pikey, did you leave the cover off on your Yukon when you bled it? Or did you leave it on?

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They dont want you to go all the way to lock (the max that you can turn the wheel one way) while the truck is running because it creates foam. I went to lock 30 times BEFORE starting it as stated in the directions provided with my pump. The cap was off. The idea is that by turning the wheel while the truck is off, you are moving the fluid with your rack or gearbox thru the system. the method also helps to make sure that you have enough fluid in the system before you start it. If you do not turn the wheel from side to side before you start it, when you do start it the fluid reservoir will most likely empty as the pump fills your empty lines. this is when foaming and pump damage can occur as you basically run the pump dry for a few seconds. I would just suggest that you try the method of turning the wheel from lock to lock 30 times before you start it. If it does nothing to help you then you are only out 5 minutes of your time. If it does what it did on my truck it will save you time as you will not be waiting for foam to subside so you can get it bled and filled to the proper level